Magnetic printer



1957 E. E. MASTERSON 2,802,049

MAGNETIC PRINTER Filed Aug. 9, 1955 FIG 5 INVENTOR.

EARL E. MASTERSQN AGENT United States Patent 2,802,049 MAGNETIC PRINTER Earl E. Masterson, Bryn Mawr, Pa., assignor to Sperry ,Rand Corporation, New York, N. Y., a corporation of Delaware Application August 9, 1955, Serial No. 527,296 12 Claims. 01. 1782.8)

This invention relates to magnetic printers, and more particularly to devices in which a drum of magnetizable material may be magnetized according to the shape of the characters to be printed. The present invention concerns itself with the construction and mode of operation of theprinting head which performs the magnetizing operation.

A primary object of this invention is to provide a magnetic printer which is simple in construction.

Another object of the invention is to provide a magnetic printer which can be controlled by a tape reading device in conjunction with a very simple form of control system.

Another object of the invention is to provide a simple printing head for magnetic printers.

.An additional object of the invention is to provide magnetic printing means which is reliable in operation.

In carrying out the invention, a magnetic head is provided in which the characters to be printed are formed of magnetic material, and the series of characters is arranged in the shape of a helix. The printing head, which is preferably a helical member having the foregoing characters mounted thereon in said helical path, is rotated about its axis while being moved laterally along said axis. The rate of lateral movement .is such that each character of the helix passes each of a plurality of spaced spots where printing may take place. .By selectively energizing a coil, magnetic flux may be passed from the printing head into the magnetizable material at desired instants, so as to print the desired characters at the desired spots on the magnetizable material. A control system for controlling this device is also disclosed. Further details will appear as this description proceeds.

In the drawings:

Figure 1 is an elementary view of the relation of a drum of magnetizable material and the printing head.

Figure 2 is a developed view of the surface of the printing head.

Figure 3 is .a cross-sectional view of the apparatus.

Figure 4 is a cross-sectional view of the printing head and the mechanism for rotating the same.

Figure 5 ,is a detailed view, taken along the line 55 of Figure 4.

In ,Figure ,1, the .printing head is in the shape of a one-turn helix and has the characters to be printed formed thereon. These characters are arranged according to a helicalpath, and are of magnetic material. The remainder of the printing head .10 may also be made of magnetic materiaLif the characters themselves are raised and stand out so that they more closely approach the :rnagnetizable drum 12 than any other part of the printing head 10. While any characters may be placed on the drum, for purposes of illustration, the alphabet from A to Z is shown.

In the normaloperation of the device, the printing head 10 is rotated about its axis and since the stationary rod 11 upon which it moves is threaded, the head 10 moves to the right as it is rotated. For each complete rotation of printing head 10, the head moves to the right along the rod 11 a distance equal to that between two parallel planes that are perpendicular to the axis of the rod 11, and respectively pass through the letters A and Z. As a result, there are certain predetermined discrete spots on the drum 12 where printing may take place, and each letter of the alphabet passes each such spot while the printing head 10 is moving from one end of the rod 11 to the other end thereof. Thus, it is merely necessary, in order to perform the printing function of the invention, to pass a magnetic flux from the printing head 10 into the magnetizable drum 12 at the proper instants during the travel of the head 10 along the rod 11. This will place magnetic configurations on the several spots of the drum 12in accordance with the information to be printed. The drum 12 is rotated in step-by-step fashion, that is, after each horizontal line across the drum has been printed the drum 12 is stepped forward. As the drum 12 is stepped forward from time to time, the magnetizable material will pass through a dusting box 22, wherein particles will cling to the drum, according to the shape of the characters which have been magnetically printed upon the drum 12. As the printed portions of the drum 12 then pass from the dusting box, they move to the printing mechanism 23 to 26 inclusive. Here the paper 23 is fed .from spool 24 to another spool 25. It is moved by virtue of pressure roller 26 which presses the paper tightly against the surface of the drum 12, and as the drum 12 rotates, it presses the magnetic particles adhering thereto onto the paper 23 and thereby effects a form of printing readable by the human eye.

The details of the raised configurations on head 10, the magnetic drum 12, the dusting box 22 and the printing mechanism 23 to 26 inclusive, have not been descirbed in detail, in view of the fact that these devices have been previously described in one or more of the following:

The copending application of John Presper Eckert, Jr. and J. C. Sims, Jr., Serial No. 221,362, filed April 17, 1951, for: Method and Apparatus for Magnetic Printlngi7;

The copending application of John Presper Eckert, Jr. and John C. Sims, Jr., Serial No. 333,574, filed January 27, 1953, for: High Speed Printer;

The copending application of John C. Sims, Jr., Serial No. 505,710, filed May 3, 1955, for: Dry Powder Ink Applicators;

The copending application of John C. Sims, Jr., Serial No. 513,131, filed June 3, 1955, for: Low Duty Cycle Magnetic Printer;

An article on Ferrography by Atkinson and Ellis, Franklin Institute Journal of November 1951;

An article on Ferromagnetography by T. M. Berry and J. 0. Hanna, appearing in the General Electric Review of July 1952;

An article entitled A survey of non-mechanical type printers by R. J. Rossheim-ACM Conference, December 12, 1952;

An article entitled Magnetic reproducer and printer by J. .C. Sims, Jr.,ACM Western Computer Conference of February 1953.

As shown in Figure 3, the printing head it) every closely approaches the drum 12. Flux is fed into the printing head 10 by reason of the curved plate 18 which stands close to the periphery of head It). The plate 18 is connected to yoke 19 by another yoke 20, and a coil 21 is wound on the yoke 20. The yoke 19 presents a large suface area to the drum 12 at two areas thereon which are widely spaced from the place where head 10 most closely approaches the drum 12. As a result, the flux density established by virtue of the yoke 19 passing flux into, or receiving flux from, the drum 12 is so small that it does not impair the operation of the device.

In order to rotate the printing head 10, there are two rods 13 and 14 respectively mounted securely in two wheels 15 and 16. The latter freely rotate on rod 11. Gear wheel 16 meshes with gear wheel 17, the latter being driven by a synchronous motor or servo-motor 27. The magnetic or paper tape 28 has two tracks thereon, one of which provides signals for controlling the rotary motion of gear 17 and therefore the angular velocity of printing head and the other track of which has signals for controlling the energization of coil 21. Pick-up heads 29 and 30 receive signals from these two tracks respectively, and feed such signals to motor 27 and coil 21 respectively.

.As a result, the head 10 is rotated about the rod 11, at the desired angular velocity. As each character on the head 10 passes each of said discrete spots (where printing may take place), the pick-up head 30 is, or is not, energized depending on whether that particular letter is to be printed at that spot. If printing is to take place by a particular character at a particular spot, the appropriate signal from the tape 28 will be picked up by head 30 and fed to coil 21 which will cause a large surge of magnetic flux to pass through the printing head 10 and into the drum 12, thus placing a magnetic configuration at the desired spot on the drum according to the character to be printed. The printing head 10 then moves on to the next discrete spot on the drum; and each character of the head 10 passes that next spot and,

if printing is to occur there, the head 30 gives the necessary impulse of current at the correct angular position of the drum 1.2 to produce the printing operation. This continues while the head 10 prints one complete line across the drum.

This invention is particularly concerned with the helicalarrangement of characters on the head 10 in combination with the rotation of the head and its lateral movement in one direction. The head 10 may be caused to return to its starting position at the left of the apparatus in any well known way, without departing from the invention; or in the alternative, the motor 27 may be arranged to reverse itself when the head 10 reaches the most right-hand position of its travel, and thereby cause the head 10 to be driven backwards by the motor 27. In this event, the signals on the tape 28 may be so arranged that printing may take place during the travel of the head 10 back to its original position.

The rod 11 is threaded and the hole through which it passes in the drum 10 is likewise threaded, and the pitch of these threads is such that each complete rotation of the head 10 will move the head laterally a distance equal to the distance between parallel planes which are perpendicular to the rod 11 and which respectively pass through the letters A and Z.

As shown in Figure 5, the rods 13 and 14 are rigidly connected at their left ends to gear wheel 16 and at their right ends to wheel 15.

I claim to have invented:

1. A magnetic printer comprising means carrying a series of characters composed of magnetic material and located along a helical path, means for rotating the first-named means about the axis of said helical path, a magnetizable member adjacent the first-named means and past which said characters pass, and means for selectively passing magnetic flux through said characters and into the magnetizable material.

2. A magnetic printer comprising means carrying a series vof characters composed of magnetic material and located along a helical path, means for rotating the firstnamed means about the axis of said helical path and simultaneously moving the first-named means along said axis, a magnetizable member adjacent the first-named means and past which said characters pass, and means for selectively passing magnetic flux through said characters and into the magnetizable material.

3. A magnetic printer comprising a cylindrical printing head having characters of magnetic material disposed thereon in a helical fashion, means for rotating the cylindrical head about its axis, magnetizable means adjacent the cylindrical head and past which said characters move, and means for selectively passing magnetic flux into the magnetizable means from the character which at the instant of application of the flux is closest to the magnetizable means.

4. A magnetic printer comprising a cylindrical printing head having characters of magnetic material disposed thereon in a helical fashion, means for rotating the cylindrical head about its axis and simultaneously moving it along its axis, magnetizable means adjacent the cylindrical head and past which said characters move, and means for selectively passing magnetic flux into the magnetizable means from the character which at the instant of application of the flux is closest to the magnetizable means.

5. A magnetic printer as defined in claim 1 in which there is in addition means for reading a source of recorded information and controlling both the rotation of the first-named means and the application of flux whereby to print the desired character in the desired location.

6. A magnetic printer as defined in claim 2, in which there is inaddition means for reading a source of record-- ed information and controlling both the rotation of the first-named means and the application of flux whereby to" print the desired character in the desired location.

7. A magnetic printer comprising magnetizable meansupon which the matter to be printed is to be recorded and means for magnetizing spaced spots along the magnetizable means according to the characters to be printed, said last-named means including all of the following: means carrying a series of characters composed of magnetic material and located along a helical path, means for;

rotating the last-named means about the axis of the helical series of characters and simultaneously moving the lastnamed means along said axis at a rate such that each character passes directly past each said spot on the magnetizable material where printing is to take place,

and means for selectively passing flux into the magnetizable means from the character which is in printing posi-' tion.

8. A magnetic printer as defined in claim 7, having a record, and means for taking firom the record signals andcontrolling the rotation of said third-named means asacter passes each of a plurality of spaced spots on the magnetizable material, a yoke extending closely adjacent large areas of both drums which areas are spaced from the region where said peripheries are closely adjacent each other, and a coil on said yoke.

10. A magnetic printer as defined in claim 9, includin 3 a record, and means for reading the record and controllingboth the speed of rotation of the second-named drum and the application of current to said coil according to the signals on the record.

11. A magnetic printer comprising a cylindrical drum of magnetizable material, a cylindrical drum having a series of characters composed of magnetic material, located thereon and arranged in a helical path, said drums' being mounted on parallel axes and having their peripheries closely adjacent each other, means for moving the second-named drum about its axis as well as along its.

axis so that each character passes each of a plurality of spaced spots along the finsbnamed drum, a U-sh-aped yoke in which the tree ends of the U are adjacent large areas of the first-named drum, the second-named drum being located between the two arms of the U, a plate of magnetic material adjacent a large area of the secondnamed drum on the portion thereof opposite that which is closely adjacent the first-named drum, and another yoke connecting said plate to the first-named yoke, and a coil on one of said yokes.

12. A magnetic printer comprising means carrying a series of characters composed of magnetic material and located along a helical path, means for rotating the firstnamed means about the axis of the helical path and simultaneously moving the first-named means along said axis a distance equal to the spacing between two parallel planes that are perpendicular to said axis and respectively intersect the two ends of the helical path 01" each revolution of the first-named means, magnetizaole means adjacent the first-named means, and means for selectively passing flux through the first-named means into the magnetizable means.

References Cited in the file of this patent UNITED STATES PATENTS 

